1. Field of the Invention
The present invention relates to a communication control method preferably applied when various information is transmitted by means of a wireless signal, for example, to construct a local area network (LAN) among a plurality of devices, and a transmission apparatus using this control method.
2. Description of the Related Art
Conventionally, in a relatively small range such as home, office or the like, when a local area network is. constructed among a plurality of apparatus such as various video apparatuses, a personal computer machine, its periphery and so on so as to transmit data handled by these apparatus, a wireless signal transmitter/receiver (a wireless transmission apparatus) is connected to each apparatus so as to enable data transmission through wireless transmission, instead of direct connection among apparatus via some signal lines.
A local area network is constructed through wireless transmission, thereby making it possible to simplify a system configuration without requiring direct connection among apparatus via a signal line or the like.
In the meantime, when a network is configured wirelessly, wireless transmission among devices in the network is required to be performed reliably without an occurrence of an error. When the network is composed of only two transmission apparatuses (radio stations), and these stations are fixedly positioned, it may be sufficient that transmission/receiving antennas or the like that the respective stations comprises are installed. If a number of radio stations exist in the network, there exist a plurality of counterparts performing wireless communication in the respective stations, occasionally making it difficult to communicate with all stations in simple settings.
To solve this problem, for example, each radio station is structured of performing diversity reception provided with a plurality of antennas with directivity. When wireless communication is performed, it may be considered that processing for selecting the best receivable antenna is performed. When the above mentioned local area network is constructed wirelessly, communications protocols required to ensure connection among stations in the network are complicated. In addition, it is required to perform cumbersome control in order to always check the presence or absence of wireless connection. Thus, wireless transmission traffic on use other than essential information transmission is likely to increase, and a plurality of electric wave arrival directions are produced for a short period of time. This problem cannot be solved by conventional diversity reception processing for simply selecting a proper receiving system.
That is, in general diversity reception, processing for supervising a signal reception state for a certain period of time and judging a system whose reception state is the best is required to judge a good receiving directional antenna. It is difficult to apply such time-consuming processing to the above mentioned wireless local area network.
It is an object of the present invention to ensure that a communication state among stations is always proper when a network system is wirelessly composed of a plurality of stations.
In a communication control method according to the present invention, at least one communication station is provided with a plurality of antennas with directivity, a communication station to which a radio signal is transmitted next time is judged by the communication station provided with a plurality of antennas, an optimal antenna performing communication with that communication station is judged based on a state when a signal from the judged communication station has been received in the past, and wireless communication is performed using the judged antenna.
According to this communication control method, communication processing is performed by switching to an optimal antenna of a plurality of provided directional antennas in a linked relation to a change of a communication station performing communication.
A transmission apparatus according to the present invention is provided with: a plurality of antennas to be selectively connected to transmission processing means for performing wireless communication with another communication station in a network; a storing means for storing information of an optimal antenna for each communication station in the network; and a control means for selecting an optimal antenna from the stored information of the storing means based on judgment of a communication station performing wireless transmission next time.
According to this transmission apparatus, selection of a plurality of antennas having directivity is properly controlled based on judgment of the communication station performing communication next time and the stored information of the storing means, an optimal directional antenna is always selected, and wireless communication is performed.